A quasi-synoptic interpretation of water mass distribution and circulation in the western North Pacific II: Circulation

  • Lingling Xie (谢玲玲)
  • Jiwei Tian (田纪伟)
  • Dunxin Hu (胡敦欣)
  • Fan Wang (王凡)


Using the data of conductivity-temperature-depth (CTD) intensive observations conducted during Oct.–Nov. 2005, this study provides the first three-dimension quasi-synoptic description of the circulation in the western North Pacific. Several novel phenomena are revealed, especially in the deep ocean where earlier observations were very sparse. During the observations, the North Equatorial Current (NEC) splits at about 12°N near the sea surface. This bifurcation shifts northward with depth, reaching about 20°N at 1 000 m, and then remains nearly unchanged to as deep as 2 000 m. The Luzon Undercurrent (LUC), emerging below the Kuroshio from about 21°N, intensifies southward, with its upper boundary surfacing around 12°N. From there, part of the LUC separates from the coast, while the rest continues southward to join the Mindanao Current (MC). The MC extends to 2 000 m near the coast, and appears to be closely related to the subsurface cyclonic eddies which overlap low-salinity water from the North Pacific. The Mindanao Undercurrent (MUC), carrying waters from the South Pacific, shifts eastward upon approaching the Mindanao coast and eventually becomes part of the eastward undercurrent between 10°N and 12°N at 130°E. In the upper 2 000 dbar, the total westward transport across 130°E between 7.5°N and 18°N reaches 65.4 Sv (1 Sv = 10−6 m3s−1), the northward transport across 18°N from Luzon coast to 130°E is up to 35.0 Sv, and the southward transport across 7.5°N from Mindanao coast to 130°E is 27.9 Sv.


North Pacific North Equatorial Current (NEC) Luzon Undercurrent (LUC) Mindanao Undercurrent (MUC) volume transport 


  1. Bingham F M, Lukas R. 1994. The southward intrusion of North Pacific Intermediate Water along the Mindanao coast. J. Phys. Oceanogr., 24: 141–154.CrossRefGoogle Scholar
  2. Fine R A, Lukas R, Bingham F M et al. 1994. The western equatorial Pacific: A water mass crossroad. J. Geophs. Res., 99(12): 25 063–25 080.CrossRefGoogle Scholar
  3. Firing E, Kashina Y, Hacker P. 2005. Energetic subthermocline currents observed east of Mindanao. Deep-Sea Res. II, 52: 605–613.CrossRefGoogle Scholar
  4. Gordon A L. 1986. Interocean exchange of the thermohaline water. J.Geophys. Res., 91: 5 037–5 046.Google Scholar
  5. Hu D. 1989. A thought on the role of western Pacific Ocean circulation in climate change in southeast China. Chin, J. Oceanol. Limnol., 7(1): 93–94.CrossRefGoogle Scholar
  6. Hu D, Cui M. 1989. The Western Boundary Current in the Far-Western Pacific Ocean. In: Progress of Western International Meeting and Workshop on TOGA CORAE, May 24–30, Picaut J, Lukas R, Delcroix T, eds, Noumea, New Caledonia., p123–134.Google Scholar
  7. Hu D, Cui M C. 1991. The western boundary current of the Pacific and its role in the climate, J. Oceanol. Limnol., 9(1): 1–14.CrossRefGoogle Scholar
  8. Hu D, Cui M C, Qu T et al. 1991. A Subsurface Northward Current off Mindanao Identified by Dynamic Calculation. In: Oceanography of Asian Marginal Seas, Elsevier. p. 359–365Google Scholar
  9. Kaneko I, Takatsuki Y, Kamiya H. 2001. Circulation of intermediate and deep waters in the Philippine Sea, J. Oceanogr., 57: 397–420.CrossRefGoogle Scholar
  10. Kashino Y, Watanabe H, Herunad B et al., 1999. Current variability at the Pacific entrance of the Indonesian Throughflow, J. Geophys. Res., 104: 11 021–11 035.CrossRefGoogle Scholar
  11. Liu Q, Pan A J, Liu Z Y. 2003. Intraseasonal oscillation and baroclinic instability of upper layer ocean in the North Equator Current, J. Oceanol. Limnol., 34(1): 94–100.Google Scholar
  12. Lukas R, Firing E, Hacher B et al. 1991. Observations of the Mindanao Current during the Western Equatorial Pacific Ocean Circulation Study (WEPOCS). J. Geophs. Res., 96: 7 098–7 104.CrossRefGoogle Scholar
  13. Lukas R, Yamagata T, McCreary J P et al. 1996. Pacific low-latitude western boundary currents and the Indonesia throughflow, J. Geophs. Res., 101: 12 209–12 216.CrossRefGoogle Scholar
  14. McCreary J P, Lu P. 1994. On the interaction between the subtropical and the equatorial oceans: The subtropical cell. J. Phys. Oceanogr., 24: 466–497.Google Scholar
  15. Nitani H. 1972. Beginning of the Kuroshio, In: Kuroshio: Physical Aspects of Japan Current. University of Washington Press, p.129–163Google Scholar
  16. Nonaka M, Xie S. 2003. Co-variations of sea surface temperature and wind over the Kuroshio and its extension: Evidence for ocean-to-atmospheric feedback. J. Climate, 16: 1 404–1 413.CrossRefGoogle Scholar
  17. Qiu B, Lukas R. 1996. Seasonal and interannual variability of the North Equatorial Current, the Mindanao Current, and the Kuroshio along the Pacific western boundary. J. Geophs. Res., 101(5): 12 315–12 330.CrossRefGoogle Scholar
  18. Qu T, Lukas R. 2003. The bifurcation of the North Equator Current in the Pacific. J. Phys. Oceanogr., 33: 5–18.CrossRefGoogle Scholar
  19. Qu T, Meyers G, Godfrey J S et al. 1997a. Upper ocean dynamics and its role in maintaining the annual mean western Pacific warm pool in a global GCM, Int. J. Climatol., 17: 711–724.CrossRefGoogle Scholar
  20. Qu T, Kagimoto T, Yamagata Y. 1997b. A subsurface countercurrent along the east coast of Luzon. Deep-sea Res. I., 44: 431–423.Google Scholar
  21. Qu T, Mistudera H, Yamagata T. 1998. On the western boundary currents in the Philippine Sea. J. Geophs. Res., 103(4): 7 537–7 548.CrossRefGoogle Scholar
  22. Qu T, Mitsudera H. Yamagata T. 1999. A climatology of the circulation and water mass distribution near the Philippine coast. J. Phys. Oceanogr., 29: 1 488–1 505.CrossRefGoogle Scholar
  23. Reid J L.1965. Intermediate waters of the Pacific Ocean, Johns Hopkins Oceanogr. Stud., 2: 85.Google Scholar
  24. Toole J M, Millard R C, Wang Z et al. 1990. Observations of the Pacific North Equatorial Current bifurcation at the Philippine coast. J. Phys. Oceanogr., 20: 307–318.CrossRefGoogle Scholar
  25. Uda M, Hasunuma K. 1969. The eastward subtropical countercurrent in the western north Pacific. J. Oceanogr., 25: 201–210.Google Scholar
  26. Wang F, Hu D. 1998a. Dynamic and thermohaline properties of the Mindanao Undercurrent I Dynamic structure. Chin. J. Oceanol. Limnol., 16(2): 122–127.CrossRefGoogle Scholar
  27. Wang F. Hu D. 1998b. Dynamic and thermohaline properties of the Mindanao Undercurrent II thermohaline structure. Chin. J. Oceanol. Limnol., 16(3): 206–213.CrossRefGoogle Scholar
  28. Wang F, Chang P, Hu D et al. 2002. Circulation in the western tropic Pacific Ocean and its seasonal variation. Chin Sci. Bul., 47(7): 591–595.CrossRefGoogle Scholar
  29. Wijffels S, Firing E, Toole J. 1995. The mean structure and variability of the Mindanao Current at 8°N. J. Geophs. Res, 100: 18 421–18 435.CrossRefGoogle Scholar
  30. Wyrtki K. 1961. Physical Oceanography of the Southeast Asian Waters, NAGA Report 2, Ins. of Oceanogr., University of California, San Diego, La Joola, CA. p.195.Google Scholar
  31. Xie L, Tian J, Hu D et al. 2009. A quasi-synoptic interpretation of the water mass distribution and circulation in the western North Pacific I. Water mass distribution. Chin. J. Oceanol. Limnol., 27(3): 630–639.CrossRefGoogle Scholar
  32. Zang N. 2008. The Distribution of Several Western Boundary Undercurrents and the Corresponding Dynamic Mechanism. Ph D Dissertation. Institute of Oceanography, Chinese Academia Science.Google Scholar
  33. Zhou H. 2006. A Study of Some Characteristics and Variability of the North Pacific Western Boundary Current System. PhD. Dissertation. Ocean University of China.Google Scholar
  34. Zhou H, Xu J, Guo P et al. 2006. A summary on studies of western boundary current system in the North Pacific Ocean. J. Mar. Science, 24: 49–59.Google Scholar

Copyright information

© Chinese Society for Oceanology and Limnology, Science Press and Springer Berlin Heidelberg 2009

Authors and Affiliations

  • Lingling Xie (谢玲玲)
    • 1
  • Jiwei Tian (田纪伟)
    • 1
  • Dunxin Hu (胡敦欣)
    • 2
  • Fan Wang (王凡)
    • 2
  1. 1.Physical Oceanography LaboratoryOcean University of ChinaQingdaoChina
  2. 2.Institute of OceanographyChinese Academia ScienceQingdaoChina

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